Full Screen Button is a simple extension for your browser that helps you full-screen the current tab.
There is also an option which let you maximize the active "video" element (if it is playing) instead of the tab. Please note that, you can disable this setting from the option's page. You can also use the keyboard shortcuts to maximize the active tab (Ctrl+Shift+F).
If you have a feature request, or found a bug to report, please fill the bug report form in the add-on's homepage (http://mybrowseraddon.com/fullscreen-button.html).